Multiple security vulnerabilities have been disclosed in various applications and system components within Xiaomi devices running Android.
"The vulnerabilities in Xiaomi led to access to arbitrary activities, receivers and services with system privileges, theft of arbitrary files with system privileges, [and] disclosure of phone, settings and Xiaomi account data," mobile security firm Oversecured said
https://blog.oversecured.com/20-Security-Issues-Found-in-Xiaomi-Devices/
they have been modified by the Chinese handset maker to incorporate additional functionality, leading to these flaws.